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Meteorology and You
Common Core State Standard: ELA: Reading Informational Text (3.1-10 through 8.1-10)
AIR MASSES AND COLD FRONTS
Here in the northeast, we know very well what cold fronts can do. They have brought us some of our most turbulent weather, ranging from
severe thunderstorms to a deep freeze. A front is the boundary between two air masses, and in
the case of a cold front, it is when cold air pushes into an area at a fairly quick pace.
AIR MASSES
Think of an air mass as a very large bubble. They are several hundred miles across, and they
each have different characteristics. There are several different classifications for air masses. Here
are the predominant ones:
• Maritime Tropical - warm and wet
• Maritime Polar - cool and wet
• Continental Tropical - warm and dry
• Continental Polar - cool and dry
During the winter, a maritime polar air mass would give us the best opportunity to see a snow
storm, while a continental polar air mass would give us dry and cold weather. Maritime air
masses are typically wetter than continental air masses. Polar air masses are colder than Tropical ones, and vice versa. If you have a continental polar air mass pushing up against a maritime tropical
air mass, the cold front between those two would be a strong one.
COLD FRONTS
Have you ever been outside during the summer on a hot and humid day, and all of a sudden a line of
thunderstorms comes seemingly out of nowhere? That very well could have been due to a cold front
moving through the area. Severe weather is caused by rising air in the atmosphere, and a cold front
causes just that. When the front approaches, it literally forces the air to rise, leading to condensation.
A cold front typically brings a narrow band of rain <http://en.wikipedia.org/wiki/Precipitation (meteorology)>
that follows along the leading edge of the cold front. These bands of rain can bring severe thunderstorms, especially during
the spring and autumn months, when the difference in temperature is higher.
One way to know when a cold front has come through is not only the cooler temperatures, but also a shift in the wind direction. The wind will typically come out of the south before the front, and from the north/northwest after the front moves
through.
Next time you watch a local weathercast, look to see if the weather person mentions any fronts. If they do, try to find the air
masses!
Did You Know
Cold fronts move faster than warm fronts, sometimes as much as 20 mph faster. This is because the
cold air behind the cold front is heavier and denser
than the warm air behind the warm front. The
heavier, denser, cold air can push the warmer lighter
air ahead of the cold front out of the way much
easier than the warm air can push the cold air ahead
of the warm front. When a cold front comes through,
the temperature can change drastically, sometimes
as much as 30 degrees in only a few hours! That’s
why sometimes in New England it can feel like we
went from summer to fall in one day.
When a cold front catches up to the warm front, it
will overtake the warm front and become occluded.
This is usually towards the end of a storm’s life
cycle, and it signals that any strong weather will be
weakening soon.
Lightning Quick
Activity
Look at a weather map on the National Weather Service’s
website (weather.gov), and try to find the different air masses.
Can you see the tropical air mass in the southern United States?
Can you see the polar air in the northern part of the country?
Are there any noticeable fronts on the map?
Search this site to find the explanation!
http://www.weatherwizkids.com/weather-forecasting.htm